Two-pass or multi-pass heat exchangers are known wherein various combinations of different heat exchanger plates are stacked together to create the desired flow pattern through the heat exchanger. In a two-pass heat exchanger, at least one of the fluid paths through the heat exchanger is divided into a first pass and a second pass, the first pass having an inlet manifold for introducing the fluid into the heat exchanger and an intermediate outlet manifold for transferring the fluid from the first pass and into the second pass, the second pass being in fluid communication with a further manifold that directs the fluid out of the heat exchanger after having completed the second pass. Accordingly, three different manifold structures are required in order to create a two-pass flow path, with one of the manifolds, i.e. the inlet manifold for one of the fluids in the heat exchanger, only extending through a portion of the heat exchanger core. Therefore, in order to create a heat exchanger having the desired two-pass flow pattern, different heat exchanger plates are required in order to form the heat exchanger core. Having a number of different plates required to form a heat exchanger increases costs associated with the heat exchanger and also adds to the complexity associated with the manufacturing of the heat exchanger. Accordingly, it is desirable to modify a conventional, single-pass heat exchanger into a two-pass (or multi-pass heat exchanger) without requiring the use of various different heat exchanger plates and without requiring an additional manifold structure.